This invention is generally directed to electrophotographic imaging processes, and more specifically xerographic imaging processes wherein there is avoided the localized accumulation of undesirable toner debris on the photoconductive imaging member. With the process of the present invention, there are permitted unwanted toner spots or comets, that is the prevention of the localized accumulation of undesirable toner debris on a photoconductive imaging member present in an imaging apparatus, which debris can encompass sufficient areas of the member thereby causing unwanted toner spots on the final developed output copies. In one embodiment, thus the present invention is directed to electrophotographic imaging processes which comprise the formation of an electrostatic image on a photoconductive imaging member, thereafer developing the image formed with a toner composition containing therein certain sulfur containing organopolysiloxane waxes, subsequently transferring the image to a suitable substrate, and permanently affixing the image thereto. In addition, the present invention is directed to imaging processes wherein offset preventing fluids such as silicone oils and the complex apparatuses associated with the use of such oils are avoided. Accordingly, there are permitted with the process of the present invention less complex systems and reduced maintenance of the imaging apparatus, while simultaneously avoiding the formation of undesirable toner debris or comets on the imaging member during the electrostatic imaging process.
Developer and toner compositions with certain waxes therein are known. For example, there are disclosed in U.K. Patent Publication No. 1,442,835 toner compositions containing resin particles and polyalkylene compounds, such as polyethylene and polypropylene of a molecular weight of from about 1,500 to 6,000, reference page 3, lines 97 to 119, which compositions prevent toner offsetting in electrostatic imaging process. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. Also, many patents disclose the use of metal salts of fatty acids for incorporation into toner compositions, such as U.S. Pat. No. 3,655,374.
Further, there is illustrated in Japanese Publication Abstract 130036/78 the incorporation of silicone resins into toners; while Japanese Patent Publication Abstract 48243/79 discloses the inclusion of silicone oils in toner compositions. Moreover, there are illustrated in Japanese Publication Abstracts 52,640; 55,954; 130,048; and 60,754 toners with silicone oils that enable the substantial elimination of offsetting. Furthermore, patents of background interest include U.S. Pat. Nos. 4,214,549 relating to the selection of functional silicones with a Viton fuser roll; 4,064,313; 4,142,982; 4,075,362; 4,287,280; 4,469,750; 4,142,982 discloses a low molecular weight solid silicone varnish as a toner additive; and 4,515,884. Also, disclosed in U.S. Pat. No. 3,346,405 are mercaptoalkyl substituted organopolysiloxanes, while U.S. Pat. No. 3,565,937 describes a method for preparing mercaptoalkyl organosilanes in which a silicon hydride group is added across the double bond of a sulfur substituted olefin. Other patents with similar disclosures include U.S. Pat. Nos. 3,388,144 and 4,046,795. None of the aforementioned prior art, however, illustrates the use of toner compositions with the novel organopolysiloxanes described herein, which toners are especially useful in electrostatic imaging systems wherein the formation of comets is substantially eliminated.
Moverover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there are illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions. Also, in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, there are disclosed positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds inclusive of cetyl pyridinium chloride. Other representative prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; and 4,394,430.
Other prior art of interest includes U.S. Pat. No. 4,517,272, which illustrates a silicone oil as a toner additive; 4,311,779, wherein silicone oils are added to styrene butadiene toner resins; 4,430,408, which illustrates the addition of liquid or solid silicones to toner compositions; and 4,568,642, which discloses the use of silicone oil with a functional group (amine) in a toner. Patents of background interest include British Pat. No. 1,402,010; U.S. Pat. Nos. 2,986,521; 3,974,078; 4,101,686; 4,556,624 and 4,565,773.
Additionally, illustrated in copending application U.S. Ser. No. 103,338 entitled Toner Developer Compositions With Sulfur Containing Organopolysiloxane Waxes, the disclosure of which is totally incorporated herein by reference, are imaging methods with toner compositions comprised of resin particles, pigment particles, and a sulfur containing organopolysiloxane wax, specific waxes being of the formula as illutrated, for example, in claim 2 of the aforementioned application. These sulfur waxes are also incorporated into the toner compositions selected for the process of the present invention. Furthermore, in copending application U.S. Ser. No. 004,939 with a filing date of Oct. 1, 1987, entitled Toner and Developer Compositions With Polymeric Alcohol Waxes, the disclosure of which is totally incorporated herein by reference, there are disclosed toner compositions comprised of resin particles, pigment particles, and a wax component comprised of polymeric alcohols of the formula indicated in claim 1, for example; and wherein n is a number of from about 30 to about 300. In this copending application with a filing date of Jan. 20, 1987, it is indicated that the toner and developer compositions of this invention simultaneously prevent the localized accumulation of undesirable toner debris upon the imaging member, which debris can encompass sufficient areas of the photoconductive members to permit unwanted toner spots to be present on the final developed output copy.
Although the above described toner and developer compositions are suitable for their intended purposes, that is electrophotographic imaging processes, for example, there is a need for improved processes wherein toner accumulation or cometing is avoided. More specifically, there remains a need for electrophotographic imaging processes with toner compositions containing certain organopolysiloxane waxes, and wherein the localized accumulation of undesirable toner debris upon photoconductive imaging members is eliminated thereby avoiding unwanted toner spots or comets on the final developed output copies. There also remains a need for xerographic imaging processes wherein copies of high quality with no background deposits are obtained, and wherein localized accumulating of undesirable toner debris on the photoconductive imaging member is avoided. This is also a need for positively charged toner compositions with certain organopolysiloxane waxes as illustrated hereinafter, which waxes may be present as external or internal components. Furthermore, there remains a need for toner compositions containing certain organopolysiloxane waxes, which compositions contain thereon a constant triboelectric charging value of from about 10 to about 30 microcoulombs per gram, and wherein these compositions are particularly useful in electrophotographic imaging processes that avoid toner accumulation or cometing on the imaging members selected.